Printed ribbons are a popular way to recognize achievements or show support at social, athletic, academic and political functions. The ribbons can be adorned with any of an infinite number of designs or text. In a typical printed ribbon production operation, rolls of ribbon-material tape are processed into individual printed ribbons. The tape, generally produced in the desired width of the finished ribbons, is unspooled from the rolls and printed with a desired pattern. In some operations, the printed tape is next cut into individual ribbon lengths, then dried by some combination of heaters and blowers, and fed to a stacker that guides the dried ribbons into stacks for boxing. In other operations, the printed tape is dried first, then cut into ribbons.
In processing a roll of tape into individual printed ribbons, control of the timing of the various operations is important. Various rollers and belts must incrementally advance the tape for each print cycle, in synchronization with the operation of the printer, the cutter, and the drier, in order to print the tape at proper intervals and cut ribbons of the proper length.
Traditionally, printed ribbons are formed of a woven material, usually satin. This material has been very successfully employed, but raises several production concerns. In most operations, the tape rests on a printing surface or platen as a printing head lowers onto and applies ink to the tape. During printing, ink can penetrate the woven material, often soaking through to the platen. As ink builds up on the platen, it gets tacky. The woven tape then sticks to the platen, preventing the tape from being properly advanced in synchronization with the printing and cutting operations. In order to remedy this, the operation must periodically be interrupted, usually once or twice during a typical run of about two hundred ribbons, in order to clean the platen to insure that the process can continue smoothly.
Further, in many printing operations, a vacuum or the like draws air through a porous platen to hold the tape in position for printing. Just as the platen can get tacky during a print run, so can the printing head, which can cause the tape to stick to the printing head as it retracts after printing. Because air passes easily through porous woven ribbon material, the vacuum under the platen is often unable to hold down tape which has adhered to the retracting print head, which can smudge the wet ink, ruining the ribbon. Additionally, woven ribbon material is relatively flimsy, causing it to sometimes stick to the platen or other parts of the machine, as it is fed by the rollers. This sticking problem is particularly troublesome at points in the operation where rollers or belts advance the tape from behind, for example, to position the tape for cutting. If sticking occurs at one of these locations, it can lead to mistakes in printing or cutting, as well as complications in stacking and boxing.
In addition to production concerns, the satin ribbon has limitations that restrict its commercial appeal. A trend has evolved in the decorating and gift wrap industries to employ polyvinyl chloride (PVC or vinyl) sheets that are metallized on one side ("single-metallized" ), giving the material a brilliant, shiny look. It is desirable to provide ribbons which give a similar visual impression, but which better lend themselves to being printed upon than single-metallized vinyl ribbons. Vinyl is quite heat sensitive, making it challenging to dry the ribbons quickly. Traditional drying temperatures can ruin the ribbons. Higher blower speeds can compensate for the lower temperatures, but can blow the ribbons out of position and complicate stacking and boxing. Thus, production speeds must decrease if single-metallized vinyl ribbons are to be allowed to dry properly at lower temperatures. In addition, ribbons formed of the vinyl material do not stand up well to storage in hot environments. The ribbons will often curl or melt if left in a non-ventilated store room or vehicle on a hot day.
Static electricity also poses a major barrier to the use of a vinyl material in the above-described processes, especially where silk-screen printing techniques are employed, resulting in even further production delays. As discussed, the timing of the various steps in the printing operation is important, and this can be very difficult to maintain if static electricity is not adequately controlled. If the rollers and belts cannot properly advance the tape in synchronization with the timing of these operations, due to static electricity, production can either grind to a halt or result in worthless ribbons.
Static electricity can cause the tape to stick to rollers so that, instead of advancing, the tape continuously winds back on the rollers, causing the machine to jam. The tape can also cling to the platen so that it will not advance properly, preventing proper printing or cutting. Static electricity build-up can cause the tape to cling to other parts of the machinery as well, so that the tape will not properly feed past the cutter, resulting in uneven cuts and worthless ribbons. Also, once cut, the still-wet ribbons can cling to the cutter itself or the nearby machinery, again interrupting the process and usually smudging the ink, rendering more ribbons worthless. Once cut, the single-metallized vinyl ribbons are typically very light, and any excess static charge can cause the ribbons to repel one another, or the machinery, and jump out of alignment, requiring the operator to individually sort the ribbons by hand. As for those ribbons that do make it to the end of the printing line, they can cling to the stacker rather than sorting neatly. Each of these consequences of the build-up of static electricity can contribute to a major overall drain on production levels.
In order to reduce such detrimental effects of static electricity, use of certain static elimination devices can be helpful. One such device is a static neutralizing bar, a variety of which is commercially available from Simco, a division of Illinois Tool Works Company. These static bars produce an electric field by applying voltage to metal emitters in close proximity to a ground. This field causes nearby air molecules to ionize. As the charged ribbon passes through the field, it will attract the ions to neutralize any charge, helping to reduce the static build-up on either side of the ribbon. However, the cost of these static bars, coupled with the transformers for operating them, can be quite expensive, relative to the overall cost of printing such ribbons. Also, such devices can be introduced only where the printing machinery permits. In a typical operation for printing on satin tape, the use of only one or two such static bars is usually sufficient. In the case of a material such as vinyl, however, for which static is a greater problem, additional static bars will often be required. However, even these measures are usually not sufficient in the case of single-metallized vinyl ribbons.
The various problems caused by static electricity greatly increase labor requirements, reduce productivity, and make it very difficult to fill orders in a timely and cost-effective manner, even with the use of static bars and ionized blowers. With traditional satin ribbons, all that is generally required with this type of printing operation, in addition to the person operating each print head, is one person to catch and box ribbons for each two printing lines. But when printing single-metallized vinyl ribbons, it has been necessary to have many additional workers assigned to each printing line just to pick up, sort and stack the ribbons into boxes, one or two at a time. Even then, substantial amounts of time and material can be wasted, increasing the cost of each production run.
Like the metallized vinyl sheets used in the decorative industries, other single-metallized materials are know in the art. Published application WO 94/29127 of Falaas et al. discusses metallized film, for use in decorative articles, formed of a 20-28 .mu.m thick polyurethane substrate upon which is deposited a continuous, opaque layer of metal, which can be aluminum. The metallized film can optionally include additional layers such as a primer layer, a color layer, and an overlying, protective clear coat layer.
Published application WO 82/03202 of McDermott discusses a metallized plastic film-coated paper laminate, for use as a decorative wrap, formed of a paper base layer, a polyester film extruded onto the paper base layer, and a metallic layer deposited onto the free surface of the polyester film. A print coat, commonly available from ink manufacturers, may be applied to the metallic layer to enhance its printability, and the metallic layer may also be overprinted with a design.
U.S. Pat. No. 5,427,235 to Powell et al. discusses an overwrap of a cigarette package that includes a polyester film substrate layer, preferably polyethylene terephthalate (PET), having a thickness ranging from about 0.25 to about 1.25 mil. A metal layer 14, preferably aluminum, is disposed on one surface of the substrate layer. The metallized PET film is imprinted on either surface with a printing layer, which may include transparent and opaque inks applied with conventional rotogravure or flexographic printing techniques. Depending upon the ink formulations used, it may be necessary to prime coat the surface of the base layer with an adhesion promoting material, such as polyethylene amine. The films are slit into widths appropriate for the cigarette package overwrapping machinery, and then wound onto rolls. The web is later cut into appropriate lengths to form individual overwraps.
However, none of these single-metallized materials overcomes the static problems discussed above.
It has also been contemplated to metallize a film on both sides ("double-metallize" ), for example in the food and film packaging industries, in order to minimize light passage through the packaging.
Also, U.S. Pat. No. 5,362,374 to Chang discusses a method for making a decorative sticker, which includes applying a metal coating to both sides of a 20 .mu.m thick polyester base film. A binder layer is applied in a predetermined pattern on the top surface of the polyester film, and printing is done with ink and gold foil on the remaining portion of the top surface. The sticker is then cut into the desired shape.
However, none of these materials or disclosures contemplates or suggests any solution to the above-discussed problems of preparing decorative, printed ribbons from a metallized film.